Complete the square to solve the following quadratic equation: x2+2x−8=0.(1 point)

Question

Responses

x=10, x=−8
x equals 10 , x equals negative 8

x=−10, x=8
x equals negative 10 , x equals 8

x=2, x=−4
x equals 2 , x equals negative 4

x=−2, x=4

Answer 1

To solve the quadratic equation \( x^2 + 2x - 8 = 0 \) by completing the square, we follow these steps:

1. Move the constant to the right side of the equation: \[ x^2 + 2x = 8 \]

2. To complete the square, take half of the coefficient of \( x \) (which is 2), square it, and add it to both sides. Half of 2 is 1, and squaring it gives 1: \[ x^2 + 2x + 1 = 8 + 1 \] This simplifies to: \[ (x + 1)^2 = 9 \]

3. Now, take the square root of both sides: \[ x + 1 = \pm 3 \]

4. Solve for \( x \):

   • From \( x + 1 = 3 \): \[ x = 2 \]
   • From \( x + 1 = -3 \): \[ x = -4 \]

Thus, the solutions to the equation \( x^2 + 2x - 8 = 0 \) are: \[ x = 2 \quad \text{and} \quad x = -4 \]

Hence, the correct response is: x=2, x=−4 (x equals 2, x equals negative 4).